CA2027569C - Cement setting accelerator and method of manufacturing the same - Google Patents
Cement setting accelerator and method of manufacturing the sameInfo
- Publication number
- CA2027569C CA2027569C CA002027569A CA2027569A CA2027569C CA 2027569 C CA2027569 C CA 2027569C CA 002027569 A CA002027569 A CA 002027569A CA 2027569 A CA2027569 A CA 2027569A CA 2027569 C CA2027569 C CA 2027569C
- Authority
- CA
- Canada
- Prior art keywords
- weight
- parts
- cement
- sintered body
- setting accelerator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/06—Oxides, Hydroxides
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/0093—Aluminates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/10—Accelerators; Activators
- C04B2103/14—Hardening accelerators
Abstract
The present invention provides a cement setting accelerator comprising 100 parts by weight of a sintered body, 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime powder and a method of manufacturing the same.
The sintered body contains a predetermined ratio of 3CaO?2Na2O?5A?2O3, Na2SO4 and Na2O?A?2O3. Alternatively, a predetermine ratio of 3CaO?2Na2O?5A?2O3, Na2SO4 and 4CaO?3A?2O3?SO3 are contained in the sintered body.
Further, a raw material mixture, which is not sintered and equal in the chemical composition to the sintered body noted above, may be used in place of the sintered body. Setting and hardening of a cement paste is markedly promoted by adding a small amount of the cement setting accelerator of the present invention to the cement paste. Also, the initial setting time of the cement paste can be controlled by controlling the amount of addition of the cement setting accelerator of the present invention.
The sintered body contains a predetermined ratio of 3CaO?2Na2O?5A?2O3, Na2SO4 and Na2O?A?2O3. Alternatively, a predetermine ratio of 3CaO?2Na2O?5A?2O3, Na2SO4 and 4CaO?3A?2O3?SO3 are contained in the sintered body.
Further, a raw material mixture, which is not sintered and equal in the chemical composition to the sintered body noted above, may be used in place of the sintered body. Setting and hardening of a cement paste is markedly promoted by adding a small amount of the cement setting accelerator of the present invention to the cement paste. Also, the initial setting time of the cement paste can be controlled by controlling the amount of addition of the cement setting accelerator of the present invention.
Description
2 0 2 l 5 6 9 S P E C I F I C A T I o N
"CEMENT SETTING Accr~rlr~RAToR AND METHOD OF
MANUFACTURING THE SAME"
[Technical Field]
The present invention relates to a cement setting accelerator and a method of manufacturing the same, particularly, to a cement setting accelerator which permits promptly setting a cement composition mixed with water with a small amount of addition, and also permits controlling the cement setting and hardening time as desired by increasing the addition amount of the accelerator.
[Prior Art]
Cement setting accelerators which permit accelerating the setting and hardening of a cement composition mixed with water are disclosed in Published Examined Japanese Patent Applications 56-27457 and 55-11635. The accelerator disclosed in Application 56-27457 noted above comprises calcium aluminate, sodium aluminate and sodium carbonate. The accelerator is certainly satisfactory in its capability of accelerating the setting of a cement composition. Specifically, a cement composition mixed with the cement setting accelerator disclosed in this prior art begins to set 30 seconds to 3 minutes after mixing of the composition with water, and the cement setting is substantially completed in about 10 minutes. However, it is difficult 2027~(~9 to retard as desired the initial setting time of the cement composition containing the cement setting acce-lerator disclosed in this prior art and mixed with water.
To be more specific, a cement paste having the setting accelerator added thereto begins to set promptly. Therefore, there is the defect that the cement paste begins to set before actual use when it is transported to a preferred position from the mixed position. It should also be noted that the cement setting accelerator disclosed in Application 56-27457 noted above certainly permits producing the particular effect in the case of a so-called "dry method", in which the accelerator is mixed previously with a cement com-position and a cement paste is prepared by adding water to and mixing the composition. However, the setting acceleration effect is less than about half the level in the dry method in the case of a so-called "wet method", in which the cement setting accelerator is added to a cement paste prepared first without using the accelera-tor.
The technique disclosed in the other prior art, i.e., Application No. 55-11635, also gives rise to problems similar to those inherent in the Application No. 56-27457. In addition, the cement setting accelerator disclosed in Application No. 55-11635 is defective in that the initial setting time and the _ --3 hardening performance are greatly changed depending on the kind of cement composition to which the accelerator is added.
Under the circumstances, it is very important in this technical field to develop a cement setting accelerator which permits promptly setting a cement composition mixed with water with a small amount of addition, which permits controlling the cement setting time as desired by increasing the addition amount of the accelerator, and which also permits sufficiently promoting the setting and hardening of a cement composition even in the case of the wet method.
DISrT.QSW71~ OF THE INV~r. 110N
According to the present invention, there is provided a first embodiment of applicant's new cement setting accelerator, consisting of a composition comprising 100 parts by weight of a sintered powdery material containing 4.25 to 85% of 3CaO.2Naz0.5Al203, 0.75 to 15~ by weight of Na2SO4, and at most 95% of Na20.Al203; 5 to 70 parts by weight of an alkali metal carbonate powder; and at most 170 parts by weight of a lime powder.
The present invention also provides a method of manufacturing the aforementioned first embodiment of cement setting accelerator, characterized by comprising the steps of sintering at 1150CC or more a raw material containing 19.7 to 36.9% of Na20, 54.0 to 61.8% of Al203, 0.9 to 17.8%
of CaO, and 0.4 to 8.5% of SO3 so as to obtain a sintered body; pulverizing the sintered body; and adding 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime power to 100 parts by weight of the powder sintered body obtained by the pulverization and subsequently mixing the resultant mixture.
The present invention also provides a second embodiment of applicant's new cement setting accelerator consisting of a composition comprising 100 parts by weight of a powdery material containing 4.25 to 85% of 3CaO.2NazO.5Al203, 0.75 to 15% of NazSO4, and at most 95% of Na2O.Al2O3; 5 to 10 parts by weight of an alkali metal carbonate powder; and at most 170 parts by weight of a lime powder.
The present invention also provides a third embodiment of applicant's new cement setting accelerator consisting of a composition comprising 100 parts by weight of a sintered powdery material containing 0.8S to 84.15% of 3CaO.2Na2O.5Al2O3, 0.15 to 14.85% by weight of Na2SO4, and 1 to 99% of 4CaO.3Al2O3.SO3; 5 to 70 parts by weight of an Alkali metal carbonate powder; and at most 170 parts by weight of a lime powder.
The present invention also provides in one of its aspects a method of manufacturing the aforementioned third embodiment of cement setting accelerator, characterized by comprising the steps of sintering at 1150C or more a raw material containing 0.2 to 19.5% of Na20, 50.2 to 54.0~ of Al2O3, 18.0 to 36.5% of CaO, and 8.5 to 13.1% of SO3 so as to obtain a sintered body; pulverizing the sintered body;
and adding 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime powder to 100 parts by weight of the powdery sintered body obtained by the pulverization and subsequently mixing the resultant mixture.
Further, the present invention provides a fourth embodiment of applicant's new cement setting accelerator consisting of a composition comprising 100 parts by weight of a powdery material containing 0.85 to 84.15% of 3CaO.2NazO.5Al203, 0.15 to 14.85% by weight of Na2SO~, and 1 to 99~ of 4CaO.3Al2O3.SO3; 5 to 70 parts by weight of an alkali metal carbonate powder; and at most 170 parts by weight of a lime powder.
.,~, .......... .~
2027 56~
The cement setting accelerator according to the aforementioned first embodiment of the present invention is distinguished in that the accelerator contains a powdery material of a sintered body prepared by sintering a raw material containing Na20, Al203, CaO and SO3. The cement setting accelerator is prepared by adding suitable amounts of an alkali metal carbonate powder and a lime powder to the powdery material of the sintered body.
The sintered body used in the present invention contains 3CaO.2Naz0.5Al203, Na2SO4 and Na20.Al203. As described later, the sintered body should contain 4.25 to 85% of 3CaO.2Na20.5Al203, 0.75 to 15~ of Na2SO4, and at most 95~ Na20.Al203. Desirably, the sintered body ...
2027~
should contain 17 to 85% of 3CaO-2Na20-5A~203, 3 to 15%
of Na2S04, and at most 80% of Na20-A~203.
It should be noted that the ratio of Na20-A~203 to 3CaO-2Na20-5A~203 contained in the sintered body directly affects the setting speed and strength of the cement composition after the setting. To be more speci-fic, the cement setting speed is promoted in the case where the sintered body contains a large amount of Na20-A~203. In this case, however, the cement composi-tion after the setting fails to exhibit a sufficiently high mechanical strength. By the contrary, a sintered body containing a large amount of 3CaO-2Na20-5A~203 permits the cement composition after the setting to exhibit a high mechanical strength, though the setting speed is low in this case. It follows that it is possible to control as desired the setting speed and the hardening speed of the cement composition by suitably changing the weight ratio of Na20-A~203 to 3CaO-2Na20-5A~203 contained in the sintered body.
It should be noted in this connection that CaO
contained in the sintered body is low in its reactivity.
Thus, it is difficult to obtain a sintered body containing Na20-A~203 and 3CaO-2Na20-5A~203 in a desired ratio by simply sintering a raw material mixture containing stoichiometrically determined amounts of the raw materials of CaO, A~203 and Na20. However, the present inventors have experimentally confirmed that the 2027~6g reaction of CaO is effectively promoted if SO3 is also contained in the raw material mixture. In the case of adding SO3, the molar ratio of SO3 to CaO should be 1 : 3, as apparent from the reaction formula given below:
5A~2O3 + 3Na2O + 3CaO + SO3 ~ Na2SO4 + 3CaO-2Na2O-5A~2O3 Where the sintered body does not contain Na2O-A~2O3, and contains 3CaO-2Na2O-5A~2O3 and Na2SO4 alone, the content of 3CaO-2Na2O-5A~2O3 is 85.0% and the Na2SO4 content is 15.0%.
If the raw material mixture contains a small amount of CaO, Na2O-A~2O3 is formed in the sintered body. The Na2O-A~2O3 formation in the sintered body is decreased in proportion to the increase in the CaO content in the raw material mixture. In this case, however, 3CaO-2Na2O-5A~2O3 and Na2SO4 are also formed in the sintered body, with the result that the ratio of 3CaO-2Na2O-5A~2O3 to Na2SO4 is maintained at 85 : 15, as seen from samples CA5 to CA50 shown in Table 1 given later.
It follows that, where the sintered body does not contain Na2O-A~2O3, the sintered body consists of 85% of 3CaO-2Na2O-5A~2O3 and 15% of Na2SO4. A cement setting accelerator containing a sintered body of this com-position permits improving the mechanical strength of the cement composition after the setting, though the 2Q~6~
initial setting time of the cement paste is retarded in this case. where the sintered body contains 95% of Na2O-A~2O3, 3CaO-2Na2O-5A~2O3 and Na2SO4 are contained in the sintered body in an amount of 4.25% and 0.75%, respectively, as apparent from the ratio of 3CaO-2Na2O-5A~2O3 to Na2SO4 described above. Where the Na2O-A~2O3 content of the sintered body exceeds 95%, it is certainly possible to enable the cement setting accelerator to exhibit a high setting rate. However, the mechanical strength of the cement composition after the setting is low, making it impossible to put the cement setting accelerator to a practical use. Under the circumstances, it is important for the sintered body contained in the cement setting accelerator of the present invention to consist of the components defined in claim 1.
The sintered body is pulverized. It is desirable for the pulverized powdery material to have a Blaine specific surface area of 1500 to 8000 cm2/g. A cement setting accelerator of the present invention is obtained by adding 5 to 70 parts by weight, preferably, 30 to 70 parts by weight, of an alkali metal carbonate powder and at most 170 parts by weight, preferably, 10 to 150 parts by weight, of a lime powder to 100 parts by weight of the powdery sintered body, followed by mixing the resultant composition.
The amounts of the alkali metal carbonate powder 2027~69 and the lime powder noted above are very important in the present invention. Attentions should be paid in this connection to the setting and hardening mechanism of the cement composition involving the cement setting accelerator of the present invention. Specifically, Ca(OH)2, A~203 and S03 eluted into liquid from the Na20-A~203, 3CaO-2Na20-5A~203 and Na2S04 contained in the sintered body carry out reactions in the liquid phase with Ca(OH)2 and CaS04 eluted into liquid from the 3CaO-SiO2, 3CaO-A~203 and CaS04-2H20 contained in the cement composition so as to form a hydrate of 3CaO-A~203-3CaS04-32H20 containing a large amount of crystal water, as given below:
3Ca(OH)2 + A~203 + 3CaS04 + H20 ~ 3CaO-A~203 3Cas04 32H20 The formation of the hydrate containing a large amount of crystal water given above is determined by the relationship in the amount among CaO, A~203 and S03 contained in the setting accelerator of the present invention and in the cement composition as well as by the dissolving rate of each of these components. When it comes to the rapid setting properties, it is very important to pay attentions to the relationship in the amount between CaO and A~203 eluted from the cement paste in the initial stage. Where the powdery sintered body contained in the cement setting accelerator of the present invention is singly added to a cement composition, the amount of A~2O3 is made excessive in the reaction system, resulting in shortage of CaO and, thus, fail to form the hydrate having a large amount of crystal water. To make up for the CaO shortage, it is necessary to add CaO or Ca(OH)2. The addition amount of CaO or ca(oH)2 may be determined appropriately in view of the CaO content of the sintered body used in the present invention. In the present invention, the addition amount of a lime powder has been experimentally determined to be at most 170 parts by weight, i.e., 0 to 170 parts by weight, relative to 100 parts by weight of the powdery sintered body.
It should be noted that the elution rate of aluminum ions from the sintered body is low, making it necessary to promote the elution of aluminum ions from the sintered body. To this end, an alkali metal carbonate serving to promote the aluminum ion elution is added in the present invention. In the present invention, the addition amount of the alkali metal carbonate has been experimentally determined to be 5 to 70 parts by weight relative to 100 parts by weight of the powdery sintered body.
As described above, a first embodiment of the present invention provides a cement setting accelerator comprising 100 parts by weight of a powdery sintered body, 5 to 70 parts by weight of an alkali metal carbonate powder and at most ~70 parts by weight of ~ 202756~
a lime powder. The composition of the sintered body is particularly important in the cement setting accelerator of the present invention.
According to the present invention a method of manufacturing the aforementioned first embodiment of cement setting comprises the step of preparing a sintered body contained as a main component in the cement setting accelerator.
Specifically, the sintered body is prepared by sintering a raw material mixture containing a predetermined mixing ratio of Na2O, CaO, A~2O3 and SO3.
Sodium carbonate, sodium bicarbonate, etc. can be used as a source of Na20. Limestone, quick lime, etc. can be used as a source of CaO. A~(OH)3 can be used as a source of A~2O3 in addition to alumina. Further, CaSO4, A~2 ( SO4) 3, etc. can be used as a source of SO3. In order to obtain a sintered body defined in the present invention, the raw material mixture used should contain 19.7 to 36.9% of Na2O, 54.0 to 61.8% of A~2O3, 0.9 to 17. 8% of CaO, and 0. 4 to 8. 5% of SO3. Preferably, the raw material mixture should contain 19.7 to 34. 2% of Na2O, 54.0 to 60.6% of A~2O3, 3. 6 to 17.8% of CaO, and 1.7 to 8.5% of SO3.
The raw material mixture of the composition described above is sintered at 1150 C or more, preferably, at 1200C or more, followed by pulverizing - - 12 - 202756~
the sintered body. Then, 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime powder are added to 100 parts by weight of the resultant powdery sintered body, and the mixture is fully mixed so as to obtain a cement setting accelerator of the present invention.
Let us describe more in detail the sintered body contained in said first embodiment of the cement setting accelerator of the present invention with reference to Experiments, which were conducted by the present inventors.
BRIEF DESCRIPTION OF THE DRAWINGS
In the description which follows, each of the drawing figures 1, 2, 3 and 4 is a graph showing, for various lS quantities of added cement setting accelerator according to the present invention and according to a known commercial composition of accelerator, the degree of setting and hardening of a cement paste as a function of time, measured by the penetrating depth in needle penetration Z0 measurements.
Experiment 1:
Sodium carbonate, alumina, calcium carbonate and calcium sulfate, which are available on the market as first grade reagents, were used as the starting materials. These starting materials were mixed in a mixing ratio shown in Table 1. Since CaO is dissipated from sodium carbonate and calcium carbonate when heated to 9S0C, these starting materials were excessively used in view of the CO2 dissipation noted a~ove.
100 g of the raw material mixture was put in a platinum dish and heated to 1300C at a rate of 20C/min.
The temperature was maintained at 1300C for 30 minutes so as to sinter the raw material mixture. The sintered body 'i 2a~75~9 _ - 13 -was sufficiently pulverized with a porcelain mortar so as to prepare a powdery material. When the powdery material was identified by means of an X-ray diffractometry, various minerals were found in the resultant powdery material, as denoted by symbols CA5 to CAs~ in Table 1. Incidentally, the abbreviations shown in Table 1 and in the following description denote:
C3NzA5 ... 3CaO.2Na20.5Al203 NS ... Na2SO4 NA ,,, Na2O Al203 C4A3S ... 4CaO.3Al203.SO3 Table 1 raw material composition mineral formation (wt%) (wt%) Symbol Feature C3N2A5NS NA C4A3S Na2OA~2O3 CaO so3 CAs NA 4.250.75 95 0 36.961.8 0.9 0.4 95%
CA20 NA 34 6 60 0 30.558.9 7.2 3.4 60%
CA40 NA 68 12 20 23.355.7 14.2 6.8 20%
CA50 NA 85 15 0 0 19.754.0 17.8 8.5 0%
CA51C4A3S 84.1514.85 0 1 19.554.0 18.0 8.5 1%
CA60C4A3S 68 12 0 20 15.753.2 21.6 9.5 20%
CA80C4A3S 34 6 0 60 7.951.7 29.1 11.3 60%
CAg9C4A3S 0.85 0.15 0 99 0.250.2 36.5 13.1 99%
C~
- 202756q As seen from Table 1, the sintered bodies of samples CAs to CA50 were found to contain 4.25 to 85% of C3N2A5. 0.75 to 15% of NS and 0 to 95% of NA.
The sintered body contained in the cement setting accelerator of the present invention permits controlling the setting time of a cement paste while maintaining a predetermined mechanical strength of the cement composition. As described previously, the setting is promoted by the increase in the NA content of the sintered body. On the other hand, the setting rate of C3NzA5 is lower than that of NA. This is because C3NzA5 enables the cement composition after the setting to exhibit a greater mechanical strength. Incidentally, NS is a reaction product between Na20 and S03 serving to improve the reactivity of CaO in the process of forming 3CaO.2Na20.5Al203 and Na2O.Al2O3, as described previously.
In other words, NS is not particularly relevant to the setting and hardening of the composition.
The second embodiment at cement setting accelerator according to the invention is very close to the first embodiment thereof, the sole difference being that the raw material mixture, which is sintered in the first embodiment is not sintered in the second. To be more specific, the composition of the second embodiment is the same as that of the first, except that 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime powder are added in the accelerator of the second embodiment to 100 parts by weight of a powdar mixture consisting of 4.25 to 85% of 3CaO.2NazO.5Al2O3, 0.75 to 15%
of Na2SO~, and at most 95% of Na20.Al203. In both embodiments, the reasons for the mixing ratio of the components of the cement setting accelerator are the same.
The cement setting accelerator of the second embodiment is somewhat inferior to the first, in the effect of promoting the setting and hardening of a cement composition, but is superior to the conventional cement setting accelerator in ~ 0~ 7~b9 the particular effect noted above.
In the present invention according to the aforementioned third embodiment, a sintered body is used as a main component of the cement setting accelerator, as in the first embodiment. However, the sintered body used in the third embodiment and containing 3CaO.2Na20.5A1203, Na2SO4 and 4CaO.3Al203.SO3 differs in composition from that used in the first. To be more specific, the sintered body used in the third embodiment contains 0.85 to 84.15% of 3CaO.2Na20.5Al203, 0.15 to 14.85% of Na2SO4 and 1 to 99% of 4CaO.3Al203.SO3. Preferably, the sintered body should contain to 8.5 to 84.15% of 3CaO.2Na20.5Al203, 1.5 to 14.85%
of Na2SO4 and 1 to 90% of 4CaO.3Alz03.SO3. The reaction to form 4CaO.3Al203.SO3 within the sintered body is as follows:
A
8A~2O3 + 3Na2O + 7CaO + 2SO3 3CaO-2Na2O-5A~2O3 + Na2SO4 + 4CaO-3A~2O3-SO3 The reaction given above takes place in the case where the raw material contains at most 19.5% of Na2O
and at least 18.0% of CaO. The formation of 4CaO-3A~2O3-SO3 is increased with decrease in the Na2O
content and with increase in the CaO content of the raw material. In the case of using the sintered body according to the third embodiment, the setting o~ the cement paste is retarded with increase in the content of 4CaO-3A~2O3-SO3, but is promoted with increase in the content of 3CaO-2Na2O 5A~2O3. The mineral components of the sin-tered body are substantially the same in the effect given to the mech~n;cal strength of the cement com-position after the setting. In an extreme case where Na2O is not contained in the raw material, 4CaO-3A~2O3-SO3 is formed in an amount of 100%. In this case, the setting of the cement paste is so much retarded as to make it substantially impossible to put the cement setting accelerator to a practical use.
Where the sintered body contains 99% of 4CaO-3A~2O3-SO3, however, the cement setting accelerator produces a practically satisfactory effect. Therefore the upper limit of the 4CaO-3A~2O3-SO3 is determined to be 99%, the lower limit of the 3CaO-2Na2O-5A~2O3 and Na2SO4 contents are determined to be 0.85% and 0.15%, respec-tively, because the ratio of 3CaO-2Na2O-5A~2O3 to Na2SO4 ~02756q should be 85 : 15 as described previously in conjunction with the first embodiment of cement setting accelerator.
On the other hand, the lower limit of the 4CaO.3Al2O3. S03 content is set at 1% in the present invention defined in the third embodiment so as to make the invention of this embodiment clearly distinct from the invention defined in the first embodiment. In this connection, the upper limits of the 3CaO.2Na2O.5Al2O3 and Na2SO4 contents are determined to ~e 84.15% and 14.85%, respectively.
The sintered body in the third embodiment at cement setting accelerator is pulverized into a powdery material, as in the first embodiment. The powdery sintered body should desirably have a specific surface area of 1500 to 8000 cm2/g. It should be noted that 5 to 70 parts by weight, preferably, 30 to 70 parts by weight, of an alkali metal carbonate powder, and at most 170 parts by weight, preferably, 10 to 150 parts by weight, of a lime powder are added to 100 parts by weight of the sintered body, and the mixture is mixed so as to obtain a cement setting accelerator according to the third embodiment. The reasons for the amounts of the alkali metal carbonate powder and the lime powder specified in this embodiment are a~in to those explained previously in conjunction with the first embodiment of the invention.
The overall invention in one of its aspects is directed to a method of manufacturing the aforementioned third embodiment of cement setting accelerator.
For manufacturing the cement setting accelerator, it is necessary to prepare first a sintered body contained as a main component in the cement setting accelerator. For preparing the sintered body, a raw material prepared by mixing a predetermined ratio of Na2O, Al2O3, CaO and S03 iS
heated at a predetermined temperature. The reactant materials of Na2O, Al2O3, CaO and S03 are those explained previously in conjunction with the method of manufacturing ~21569 the first embodiment of accelerator. To reiterate, sodium carbonate and sodium bicarbonate can be used as sources of Na2O. Al2(OH)3 can also be used as the Al2O3 material in addition to alumina. CaSO4, Al2tSO4)3, etc. can be used as the S03 material. Further, limestone, quick lime, etc. can be used as the CaO material. In order to obtain a sintered body of the composition defined in the present invention, it is necessary to use a raw mateial containing 0.Z to 19.5% of Na2O, 50.2 to 54.0% of A12O3, 18.0 to 36.5% of CaO
and 8.5 to 13.1% of SO3. Preferably, the raw material should contain 2.0 to 19.5% of Na2O, 50.6 to 54.0% of Al2O3, 18.0 to 34.8% of CaO and 8.5 to 12.6% S03. The raw material of the composition noted above should be sintered at 1150C
or more, preferably, at 1200C or more, as in the manufacture of the first embodiment of product. The sintering conditions are equal to those explained previously in conjunction with the manufacture of the first embodiment. The sintered body is pulverized into a powdery sintered body, and 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime powder are added to 100 parts by weight of the powdery sintered body so as to obtain a desired cement setting accelerator of the present invention.
The aforementioned fourth embodiment of cement setting accelerator within the present invention is very close to the third embodiment thereof, the sole difference being that a mixture of the individual raw materials, which are contained in the sintered body used in the third embodiment, is used in the fourth embodiment of the invention in place of the sintered body. To be more specific, 5 to 70% parts by weight of an al~ali metal carbonate powder and at most 170 parts by weight of a lime powder are added in the invention of claim 6 to 100 parts by weight of a powdery mixture consisting of 0.85 to 84.15%
of 3CaO.2Na2O.5Al2O3, 0.15 to 14.85% of Na2SO4 and 1 to 99%
of 4CaO.3Alz03. S03 SO as to prepare a desired cement setting accelerator. The reasons for the mixing ratio of the components as well as the preferred ranges of the contents of the individual components of the accelerator specified in relation to the fourth embodiment produce the same as in the case of the third embodiment. The cement setting accelerator of the fourth embodiment is somewhat inferior to that of the third, in the setting rate of the cement paste and the mechanical strength of the cement composition after the setting, ~ut is superior to conventional cement setting accelerators.
Fxperiment 2:
First grade reagents of sodium carbonate, alumina, ...
h'~' 2027~69 calcium carbonate and calcium sulfate, which are available on the market, were ùsed as the raw materials, as in Experiment 1. These raw materials were mixed as denoted by samples CA5l to CAgg in Table 1. As pointed out previously, CO2 is dissipated at 950C from sodium carbonate and calcium carbonate contained in the raw material mixture in the process of sintering the raw material mixture. In view of the dissipation, these sodium carbonate and calcium carbonate were used in excess amounts.
The raw material mixture was sintered and, then, the sintered body was sufficiently pulverized in a porcelain mortar. The pulverized sintered body thus prepared was identified by means of X-ray diffraction so as to confirm the mineral formation as denoted by symbols CA51 to CAgg in Table l.
The effect of the cement setting accelerator was confirmed as follows. Specifically, each of sintered bodies prepared as in Experiments l and 2 was pulverized until the pulverized particles had a diameter of 0.3 mm or less. Then, sodium carbonate and slaked lime were mixed with the pulverized sintered body in amounts shown in Table 2 so as to prepare a cement setting accelerator. On the other hand, a cement paste was separately prepared by sufficiently mixing in a synthetic resin container having an inner volume of 200 m~ a wate/cement mixture mixed at a ratio of 0.6.
The samples of the cement setting accelerator were added to 160 g of the cement paste in outer percentage by weight of 5, 8, 15 and 20%, respectively. The mixture was rapidly mixed with a spatula for about lO seconds so as to permit the cement setting accelerator to be mixed sufficiently with the cement paste. After the surface was smoothed, the mixed cement paste was allowed to stand still so as to measure the initial setting time and final setting time of the cement paste setting in accordance with the test method specified in JIS R5201.
In this test, a weight of 300 g was put on a setting tester. Table 2 shows the results. Table 2 also shows comparative experiment, i.e., use of a rapid setting agent CAo consisting of NA, sodium carbonate and slaked lime, and use of a cement setting accelerator CAo1 available on the market. Incidentally, the parenthe-sized symbols shown in Table 2, i.e., (CA20), (CA40), (ca6o)~ and (CA80), denote that the compositions equal to those of CA20, CA40, CA60 and CA80 were used simply as mixtures of the individual powdery components, not as minerals as in the symbols without the parentheses.
Table 2 Mineral Composition or Composition of Cement Symbol Mixture Composition (wt~) Setting ~ccelrator (wt%) _ mineral sodium slaked C3N2A5 NS NA C4A3S or carbonate line mixture CAo - - 100 - 40 20 40 CA5 4.250.75 95 - 40 20 40 CA50 85 15 - _ 60 20 20 CA51 84.1514.85 0 1 60 20 20 w CAgg 0.850.15 - 99 95 5 0 CAol 34 6 60 - 40 20 40 (CA20) 34 6 60 - 40 20 40 (CA40) 68 12 20 - 50 20 30 ~
(CA60) 68 12 - 20 70 20 10 rs (CA80) 34 6 _ 60 85 15 _ C~
(Continued Addition Amount of Cement Setting Accelerator to Cement (outer % by weight) 5 % 8 % 15 % 20 %
Symbol initial final initial final initial final initial final time time time time time time time time (min., (min., (min., (min., (min., (min., (min., (min., sec.) sec.) sec.) sec.) sec.)sec.) sec.) sec.) or or or or CAo 2 '60 'more 2 ' 60 'more 10"60 'more 10" 60 'more CA5 2'30"3:0' 2' 30' 15"10' - -CA20 2'30" 27' 1' 20' 15" 5' 10" 3' CA40 5' 27' 4' 14' 1'30" 5' 1' 3' CA50 10' 35' 5' 17' 2'30" 10' 1'30" 4' CA51 12 36 ' 6 ' 18 ' 2 ' 40" 10 ' 1 ' 40" 4 ' CA60 23' 47' 10' 22' 5' 15' 2' 5' CA80 33' 50' 20' 35' 7' 20' 6' 20' CAgg - - 30 ' 55 ' 15 ' 45 ' 10 ' 30 ' or or or CAol 12'60'more 3'60'more 10" 60'more 10" 10' or (CA20 ) 10 '50 ' 2 '60'more 10" 10' 10" 7 ' or or (CA40 ) 15 '60'more 2 '60'more 10" 10' 10" 5 ' 2 or (CA60) 12'60'more 2' 30' 15" 11' 30" 8' or or (CA80) 13'60'more 2'60'more 3' 17' 3' 15' C.r~
CD
As seen from Table 2, any kind of the cement setting accelerator of the present invention exhibits an excellent rapid setting property. Figs. 1 to 4 show the results of the experiments, covering the different adding amounts of the cement setting accelerator, respectively. It is clearly seen from Figs. 1 to 4 that the cement setting accelerator of the present invention exhibits an excellent rapid setting and hardening pro-perty. It is important to note that the cement setting accelerator of the present invention makes it possible to control the setting time by controlling the mineral composition and the adding amount of the cement setting accelerator. It should also be noted that the parenthe-sized samples of (CA20), (CA40), (CA60) and (CA80) were somewhat inferior to the samples of CA20, CA40, CA60 and CAgo without the parentheses in the rapid setting pro-perty and the hardening time, but were superior to the comparative experiment of CAo and CAol, though the parenthesized samples are not shown in the drawings.
Example 1:
A raw material containing 46.4% of sodium carbonate, 47.9% of alumina, 3.4% of limestone, and 2.3%
of anhydrous gypsum was prepared by suitably mixing powdery materials of alumina (A~2O3, 99.7%), sodium carbonate (Na2O, 58.2%), limestone (CaO, 53.2%; MaO, 0.5%; Fe2O3, 0.2%; and A~2O3, 0.1%) and anhydrous gypsum (CaO, 41%; SO3, 58.7%). The raw material was sufficiently mixed and, then, sintered in a sintering furnace at 1300C i50C for 30 minutes so as to obtain a sintered body.
The resultant sintered body was found to contain 80% of NA, 17% of C3N2A5, and 3% of NS. In other words, the sintered body was found to contain 34.1% of Na2O, 60.6% of A~2O3, 3.6% of CaO and 1.7% of SO3. Then, the sintered body was pulverized into a powdery material having a Blain specific surface area of 3500 cm2/g. A
cement setting accelerator was prepared by adding 60 parts by weight of sodium carbonate and 130 parts by weight of quick lime to 100 parts by weight of the powdery sintered body thus prepared. The resultant cement setting accelerator was applied to the face in the presence of spring water in a tunneling site as follows.
In the first step, cloth was applied to provisionally stop spring water at the rate of 400 to 1000 1/min/5 m2 in a freshet portion at the face In a tunneling site, followed by placing in a cavity of the cloth a cement composition prepared by mixing 20 parts by weight of the cement setting accelerator pre-pared as above with 100 parts by weight of the ordinary Portland cement. The portion where the cement composi-tion was placed was supported with a flat plate for about 2 minutes so as to completely stop the spring water, followed by applying a concrete spraying by the ~_ 2027~69 ordinary method. An additional spring water and fall of the concrete layer were not recognized at all after the treatment.
Example 2:
A raw material containing 32.2% of sodium carbonate, 44.9% of alumina, 13.S% of limestone, and 9.4% of anhydrous gypsum was prepared by suitably mixing powdery materials of alumina, sodium carbonate, limestone and anhydrous gypsum, as in Example 1. The raw material was sufficiently mixed and, then, sintered as in Example 1 so as to obtain a sintered body.
The resultant sintered body was found to contain 20% of NA, 68% of C3N2A5, and 12% of NS. In other words, the sintered body was found to contain 23.3% of Na2O, 55.7% of A~2O3, 14.2% of CaO and 6.8% of SO3.
Then, the sintered body was pulverized as in Example 1 into a powdery material having a Blain specific surface area of 3500 cm2/g. A cement setting accelerator was prepared by adding 60 parts by weight of sodium carbonate and 90 parts by weight of quick lime to 100 parts by weight of the powdery sintered body thus prepared. The resultant cement setting accelerator was used in a tunnel-boring site as follows.
In the first step, concrete was prepared by mixing a mixture consisting of 360 kg of the ordinary portland cement, 1020 kg of a fine aggregate, 686 kg of a coarse aggregate having a maximum size of 15 mm, and ~- 2027569 205 kg of water. The concrete thus prepared was transported by a track mixer to the face of a tunneling site and sprayed through a hose including a Y-shaped branched portion to the face by a compressed air. The Y-shaped branched portion was positioned about 3 m inside the tip of the blowing nozzle mounted at the tip of the hose. The cement setting accelerator prepared as above was also sprayed by a compressed air through one of the branches of the hose such that the cement setting accelerator was added in an amount of 3 to 10% by weight (outer percentage) based on the amount of the cement contained in the concrete.
The concrete mixed with the cement setting accele-rator was sprayed through the nozzle onto the ceiling and wall of the arching tunnel. The average thickness of the concrete layer formed on the wall of the tunnel was about 20 cm. The amount of the cement setting accelerator was 3.5% on the average based on the amount of the cement contained in the concrete. The average thickness of the concrete layer formed on the ceiling of the tunnel was 20 to 50 cm. The amount of the cement setting accelerator was 6.5% on the average based on the amount of the cement contained in the concrete. In the case of the ceiling portion where 40 to 100 1/min/5 m2 of spring water was recognized, the concrete layer fell off in spite of the increase in the addition amount of the cement setting accelerator to 7% based on the amount ~_ 2027569 of the cement contained in the concrete. However, the fall was prevented when the amount of the cement setting accelerator was further increased to 9%.
On the other hand, concrete was similarly sprayed, by using a rapid setting agent available on the market consisting of calcium aluminate, sodium aluminate, sodium carbonate and lime. The amount of the rapid setting agent was 5.0% in the case of the wall of the - tunnel and 9.0% in the case of the ceiling of the tunnel on the average based on the amount of the cement con-tained in the concreta. Further, it was impossible to prevent the sprayed concrete layer from falling off in the presence of spring water, though the amount of the rapid setting agent was increased up to 15%.
Example 3:
A raw material containing 10.7% of sodium carbonate, 41.3% of alumina, 30.8% of limestone, and 17.2% of dihydrated gypsum was prepared by suitably mix-ing powdery materials of alumina (A~2O3, 98.1%),sodium carbonate tNa2O, 58.2%), limestone (CaO, 54.0%; MaO, 0.3%; and Fe2O3 0.1%) and dihydrated gypsum (CaO, 36.1%, SO3 51.9%). The raw material was sufficiently mixed and, then, sintered in a sintering furnace at 1250C
i50C for 30 minutes so as to obtain a sintered body.
The resultant sintered body was found to contain 60% of C4A3S, 34% of C3N2A5, and 6% of NS. In other words, the sintered body was found to contain 7.9% of ` ~--2027~69 Na2O, 51.7% of A~2O3, 29.1% of CaO and 11.3% of SO3.
Then, the sintered body was pulverized into a powdery material having a Blain specific surface area of 3200 cm2/g. A cement setting accelerator was prepared by adding 15 parts by weight of sodium carbonate to 100 parts by weight of the powdery sintered body thus prepared. A concrete layer was repaired as follows by using the resultant cement setting accelerator thus pre-pared.
10Specifically, vertical shaft mixer having an inner volume of 200 liters and an air compression pump were installed besides a repair portion of a concrete slab on which a train runs every hour. A flowable concrete was prepared by keanding a mixture consisting of 370 kg of 15cement, 1150 kg of a fine aggregate, 675 kg of a coarse aggregate, 150 kg of water and 1.75 kg of a fluidizing agent available on the market per cubic meter of the concrete mixture. The flowable concrete thus prepared was forwarded through the pump into a polyethylene bucket disposed at the repair portion 50 m away from the location of the concrete mixer. Fifty liters of the flowable concrete was received by the polyethylene bucket having an inner volume of 100 ~. Then, 1.1 kg of the cement setting accelerator prepared in advance was added to the concrete received in the bucket, and mixing was carried out for 2 to 3 minutes by a handy type mixer. The content of the cement setting accelerator was 6% based on the amount of the cement contained in the concrete. The mixed concrete was placed on the repair portion, followed by applying a surface-finishing treatment so as to complete the repair. Since initia-tion of the concrete setting was recognized 25 minutes after the mixing of the concrete with the cement setting accelerator added thereto, the repair work was completed without difficulty. The compression strength of a test piece of the same material was measured 1 hour after completion of the repair work. The compression strength was found to be 35 kgf/cm2, which is high enough to withstand the running of a train.
Example 4:
An agent B containing 95% or more of C3N2A5 was prepared by sufficiently mixing the raw materials con-sisting of 42.8% of alumina, 26.6% of sodium carbonate, and 40.9% of limestone as in Example 1, followed by sin-tering the raw material mixture at 1300C i50C in a sintering furnace. Likewise, an agent A containing 98%
or more of NA was prepared by sufficiently mixing the raw materials consisting of 49% of alumina and 51% of sodium carbonate, followed by sintering the raw material mixture at 1250C i50C in a sintering furnace. Then, a cement setting accelerator was prepared by uniformly mixing 24 parts by weight of agent A, 13.6 parts by weight of agent B, 2.4 parts by weight of sodium sulfate available on the market, 20 parts by weight of sodium ` ~_ 2027569 carbonate and 45 parts by weight of slaked lime.
Concrete spraying was carried out as in Example 2 by using the cement setting accelerator thus prepared.
The average amount of the cement setting accelerator used based on the amount of the cement contained in the concrete was 4.0% in the wall of the tunnel and 8.0%
in the ceiling of the tunnel. In the water spring portion, fall of the concrete layer was prevented when the amount of the cement setting accelerator was increased to 12%.
[Effect of the Invention]
As described above in detail, the present invention provides a cement setting accelerator which permits the setting of cement to be carried out in a short time and also permits controlling the initial setting time of the cement composition over a range of about 30 minutes starting with the time immediately after the addition of the cement setting accelerator. It follows that the cement setting accelerator of the present invention can be effectively used for the spraying of mortar or concrete which is required to be viscous at the time of spraying and to be set rapidly after the spraying.
Also, since the initiation time of the cement paste setting can be controlled over a wide range as noted above, it is of course possible to use the accelerator of the present invention as the broadly used cement setting accelerator requiring a determination in advance 20~75~9 of the setting reaction.
What should also be noted is that the cement setting accelerator of the present invention can be used both in a wet method in which the accelerator is added to a cement paste and in a dry method in which the accelerator is mixed previously with the cement. It follows that the cement setting accelerator of the pre-sent invention can be effectively used in a method which is popular nowadays, i.e., the method in which a cement paste mixed previously is forwarded to the place of application and the cement setting accelerator is added to the cement paste forwarded to the place of application.
-
"CEMENT SETTING Accr~rlr~RAToR AND METHOD OF
MANUFACTURING THE SAME"
[Technical Field]
The present invention relates to a cement setting accelerator and a method of manufacturing the same, particularly, to a cement setting accelerator which permits promptly setting a cement composition mixed with water with a small amount of addition, and also permits controlling the cement setting and hardening time as desired by increasing the addition amount of the accelerator.
[Prior Art]
Cement setting accelerators which permit accelerating the setting and hardening of a cement composition mixed with water are disclosed in Published Examined Japanese Patent Applications 56-27457 and 55-11635. The accelerator disclosed in Application 56-27457 noted above comprises calcium aluminate, sodium aluminate and sodium carbonate. The accelerator is certainly satisfactory in its capability of accelerating the setting of a cement composition. Specifically, a cement composition mixed with the cement setting accelerator disclosed in this prior art begins to set 30 seconds to 3 minutes after mixing of the composition with water, and the cement setting is substantially completed in about 10 minutes. However, it is difficult 2027~(~9 to retard as desired the initial setting time of the cement composition containing the cement setting acce-lerator disclosed in this prior art and mixed with water.
To be more specific, a cement paste having the setting accelerator added thereto begins to set promptly. Therefore, there is the defect that the cement paste begins to set before actual use when it is transported to a preferred position from the mixed position. It should also be noted that the cement setting accelerator disclosed in Application 56-27457 noted above certainly permits producing the particular effect in the case of a so-called "dry method", in which the accelerator is mixed previously with a cement com-position and a cement paste is prepared by adding water to and mixing the composition. However, the setting acceleration effect is less than about half the level in the dry method in the case of a so-called "wet method", in which the cement setting accelerator is added to a cement paste prepared first without using the accelera-tor.
The technique disclosed in the other prior art, i.e., Application No. 55-11635, also gives rise to problems similar to those inherent in the Application No. 56-27457. In addition, the cement setting accelerator disclosed in Application No. 55-11635 is defective in that the initial setting time and the _ --3 hardening performance are greatly changed depending on the kind of cement composition to which the accelerator is added.
Under the circumstances, it is very important in this technical field to develop a cement setting accelerator which permits promptly setting a cement composition mixed with water with a small amount of addition, which permits controlling the cement setting time as desired by increasing the addition amount of the accelerator, and which also permits sufficiently promoting the setting and hardening of a cement composition even in the case of the wet method.
DISrT.QSW71~ OF THE INV~r. 110N
According to the present invention, there is provided a first embodiment of applicant's new cement setting accelerator, consisting of a composition comprising 100 parts by weight of a sintered powdery material containing 4.25 to 85% of 3CaO.2Naz0.5Al203, 0.75 to 15~ by weight of Na2SO4, and at most 95% of Na20.Al203; 5 to 70 parts by weight of an alkali metal carbonate powder; and at most 170 parts by weight of a lime powder.
The present invention also provides a method of manufacturing the aforementioned first embodiment of cement setting accelerator, characterized by comprising the steps of sintering at 1150CC or more a raw material containing 19.7 to 36.9% of Na20, 54.0 to 61.8% of Al203, 0.9 to 17.8%
of CaO, and 0.4 to 8.5% of SO3 so as to obtain a sintered body; pulverizing the sintered body; and adding 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime power to 100 parts by weight of the powder sintered body obtained by the pulverization and subsequently mixing the resultant mixture.
The present invention also provides a second embodiment of applicant's new cement setting accelerator consisting of a composition comprising 100 parts by weight of a powdery material containing 4.25 to 85% of 3CaO.2NazO.5Al203, 0.75 to 15% of NazSO4, and at most 95% of Na2O.Al2O3; 5 to 10 parts by weight of an alkali metal carbonate powder; and at most 170 parts by weight of a lime powder.
The present invention also provides a third embodiment of applicant's new cement setting accelerator consisting of a composition comprising 100 parts by weight of a sintered powdery material containing 0.8S to 84.15% of 3CaO.2Na2O.5Al2O3, 0.15 to 14.85% by weight of Na2SO4, and 1 to 99% of 4CaO.3Al2O3.SO3; 5 to 70 parts by weight of an Alkali metal carbonate powder; and at most 170 parts by weight of a lime powder.
The present invention also provides in one of its aspects a method of manufacturing the aforementioned third embodiment of cement setting accelerator, characterized by comprising the steps of sintering at 1150C or more a raw material containing 0.2 to 19.5% of Na20, 50.2 to 54.0~ of Al2O3, 18.0 to 36.5% of CaO, and 8.5 to 13.1% of SO3 so as to obtain a sintered body; pulverizing the sintered body;
and adding 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime powder to 100 parts by weight of the powdery sintered body obtained by the pulverization and subsequently mixing the resultant mixture.
Further, the present invention provides a fourth embodiment of applicant's new cement setting accelerator consisting of a composition comprising 100 parts by weight of a powdery material containing 0.85 to 84.15% of 3CaO.2NazO.5Al203, 0.15 to 14.85% by weight of Na2SO~, and 1 to 99~ of 4CaO.3Al2O3.SO3; 5 to 70 parts by weight of an alkali metal carbonate powder; and at most 170 parts by weight of a lime powder.
.,~, .......... .~
2027 56~
The cement setting accelerator according to the aforementioned first embodiment of the present invention is distinguished in that the accelerator contains a powdery material of a sintered body prepared by sintering a raw material containing Na20, Al203, CaO and SO3. The cement setting accelerator is prepared by adding suitable amounts of an alkali metal carbonate powder and a lime powder to the powdery material of the sintered body.
The sintered body used in the present invention contains 3CaO.2Naz0.5Al203, Na2SO4 and Na20.Al203. As described later, the sintered body should contain 4.25 to 85% of 3CaO.2Na20.5Al203, 0.75 to 15~ of Na2SO4, and at most 95~ Na20.Al203. Desirably, the sintered body ...
2027~
should contain 17 to 85% of 3CaO-2Na20-5A~203, 3 to 15%
of Na2S04, and at most 80% of Na20-A~203.
It should be noted that the ratio of Na20-A~203 to 3CaO-2Na20-5A~203 contained in the sintered body directly affects the setting speed and strength of the cement composition after the setting. To be more speci-fic, the cement setting speed is promoted in the case where the sintered body contains a large amount of Na20-A~203. In this case, however, the cement composi-tion after the setting fails to exhibit a sufficiently high mechanical strength. By the contrary, a sintered body containing a large amount of 3CaO-2Na20-5A~203 permits the cement composition after the setting to exhibit a high mechanical strength, though the setting speed is low in this case. It follows that it is possible to control as desired the setting speed and the hardening speed of the cement composition by suitably changing the weight ratio of Na20-A~203 to 3CaO-2Na20-5A~203 contained in the sintered body.
It should be noted in this connection that CaO
contained in the sintered body is low in its reactivity.
Thus, it is difficult to obtain a sintered body containing Na20-A~203 and 3CaO-2Na20-5A~203 in a desired ratio by simply sintering a raw material mixture containing stoichiometrically determined amounts of the raw materials of CaO, A~203 and Na20. However, the present inventors have experimentally confirmed that the 2027~6g reaction of CaO is effectively promoted if SO3 is also contained in the raw material mixture. In the case of adding SO3, the molar ratio of SO3 to CaO should be 1 : 3, as apparent from the reaction formula given below:
5A~2O3 + 3Na2O + 3CaO + SO3 ~ Na2SO4 + 3CaO-2Na2O-5A~2O3 Where the sintered body does not contain Na2O-A~2O3, and contains 3CaO-2Na2O-5A~2O3 and Na2SO4 alone, the content of 3CaO-2Na2O-5A~2O3 is 85.0% and the Na2SO4 content is 15.0%.
If the raw material mixture contains a small amount of CaO, Na2O-A~2O3 is formed in the sintered body. The Na2O-A~2O3 formation in the sintered body is decreased in proportion to the increase in the CaO content in the raw material mixture. In this case, however, 3CaO-2Na2O-5A~2O3 and Na2SO4 are also formed in the sintered body, with the result that the ratio of 3CaO-2Na2O-5A~2O3 to Na2SO4 is maintained at 85 : 15, as seen from samples CA5 to CA50 shown in Table 1 given later.
It follows that, where the sintered body does not contain Na2O-A~2O3, the sintered body consists of 85% of 3CaO-2Na2O-5A~2O3 and 15% of Na2SO4. A cement setting accelerator containing a sintered body of this com-position permits improving the mechanical strength of the cement composition after the setting, though the 2Q~6~
initial setting time of the cement paste is retarded in this case. where the sintered body contains 95% of Na2O-A~2O3, 3CaO-2Na2O-5A~2O3 and Na2SO4 are contained in the sintered body in an amount of 4.25% and 0.75%, respectively, as apparent from the ratio of 3CaO-2Na2O-5A~2O3 to Na2SO4 described above. Where the Na2O-A~2O3 content of the sintered body exceeds 95%, it is certainly possible to enable the cement setting accelerator to exhibit a high setting rate. However, the mechanical strength of the cement composition after the setting is low, making it impossible to put the cement setting accelerator to a practical use. Under the circumstances, it is important for the sintered body contained in the cement setting accelerator of the present invention to consist of the components defined in claim 1.
The sintered body is pulverized. It is desirable for the pulverized powdery material to have a Blaine specific surface area of 1500 to 8000 cm2/g. A cement setting accelerator of the present invention is obtained by adding 5 to 70 parts by weight, preferably, 30 to 70 parts by weight, of an alkali metal carbonate powder and at most 170 parts by weight, preferably, 10 to 150 parts by weight, of a lime powder to 100 parts by weight of the powdery sintered body, followed by mixing the resultant composition.
The amounts of the alkali metal carbonate powder 2027~69 and the lime powder noted above are very important in the present invention. Attentions should be paid in this connection to the setting and hardening mechanism of the cement composition involving the cement setting accelerator of the present invention. Specifically, Ca(OH)2, A~203 and S03 eluted into liquid from the Na20-A~203, 3CaO-2Na20-5A~203 and Na2S04 contained in the sintered body carry out reactions in the liquid phase with Ca(OH)2 and CaS04 eluted into liquid from the 3CaO-SiO2, 3CaO-A~203 and CaS04-2H20 contained in the cement composition so as to form a hydrate of 3CaO-A~203-3CaS04-32H20 containing a large amount of crystal water, as given below:
3Ca(OH)2 + A~203 + 3CaS04 + H20 ~ 3CaO-A~203 3Cas04 32H20 The formation of the hydrate containing a large amount of crystal water given above is determined by the relationship in the amount among CaO, A~203 and S03 contained in the setting accelerator of the present invention and in the cement composition as well as by the dissolving rate of each of these components. When it comes to the rapid setting properties, it is very important to pay attentions to the relationship in the amount between CaO and A~203 eluted from the cement paste in the initial stage. Where the powdery sintered body contained in the cement setting accelerator of the present invention is singly added to a cement composition, the amount of A~2O3 is made excessive in the reaction system, resulting in shortage of CaO and, thus, fail to form the hydrate having a large amount of crystal water. To make up for the CaO shortage, it is necessary to add CaO or Ca(OH)2. The addition amount of CaO or ca(oH)2 may be determined appropriately in view of the CaO content of the sintered body used in the present invention. In the present invention, the addition amount of a lime powder has been experimentally determined to be at most 170 parts by weight, i.e., 0 to 170 parts by weight, relative to 100 parts by weight of the powdery sintered body.
It should be noted that the elution rate of aluminum ions from the sintered body is low, making it necessary to promote the elution of aluminum ions from the sintered body. To this end, an alkali metal carbonate serving to promote the aluminum ion elution is added in the present invention. In the present invention, the addition amount of the alkali metal carbonate has been experimentally determined to be 5 to 70 parts by weight relative to 100 parts by weight of the powdery sintered body.
As described above, a first embodiment of the present invention provides a cement setting accelerator comprising 100 parts by weight of a powdery sintered body, 5 to 70 parts by weight of an alkali metal carbonate powder and at most ~70 parts by weight of ~ 202756~
a lime powder. The composition of the sintered body is particularly important in the cement setting accelerator of the present invention.
According to the present invention a method of manufacturing the aforementioned first embodiment of cement setting comprises the step of preparing a sintered body contained as a main component in the cement setting accelerator.
Specifically, the sintered body is prepared by sintering a raw material mixture containing a predetermined mixing ratio of Na2O, CaO, A~2O3 and SO3.
Sodium carbonate, sodium bicarbonate, etc. can be used as a source of Na20. Limestone, quick lime, etc. can be used as a source of CaO. A~(OH)3 can be used as a source of A~2O3 in addition to alumina. Further, CaSO4, A~2 ( SO4) 3, etc. can be used as a source of SO3. In order to obtain a sintered body defined in the present invention, the raw material mixture used should contain 19.7 to 36.9% of Na2O, 54.0 to 61.8% of A~2O3, 0.9 to 17. 8% of CaO, and 0. 4 to 8. 5% of SO3. Preferably, the raw material mixture should contain 19.7 to 34. 2% of Na2O, 54.0 to 60.6% of A~2O3, 3. 6 to 17.8% of CaO, and 1.7 to 8.5% of SO3.
The raw material mixture of the composition described above is sintered at 1150 C or more, preferably, at 1200C or more, followed by pulverizing - - 12 - 202756~
the sintered body. Then, 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime powder are added to 100 parts by weight of the resultant powdery sintered body, and the mixture is fully mixed so as to obtain a cement setting accelerator of the present invention.
Let us describe more in detail the sintered body contained in said first embodiment of the cement setting accelerator of the present invention with reference to Experiments, which were conducted by the present inventors.
BRIEF DESCRIPTION OF THE DRAWINGS
In the description which follows, each of the drawing figures 1, 2, 3 and 4 is a graph showing, for various lS quantities of added cement setting accelerator according to the present invention and according to a known commercial composition of accelerator, the degree of setting and hardening of a cement paste as a function of time, measured by the penetrating depth in needle penetration Z0 measurements.
Experiment 1:
Sodium carbonate, alumina, calcium carbonate and calcium sulfate, which are available on the market as first grade reagents, were used as the starting materials. These starting materials were mixed in a mixing ratio shown in Table 1. Since CaO is dissipated from sodium carbonate and calcium carbonate when heated to 9S0C, these starting materials were excessively used in view of the CO2 dissipation noted a~ove.
100 g of the raw material mixture was put in a platinum dish and heated to 1300C at a rate of 20C/min.
The temperature was maintained at 1300C for 30 minutes so as to sinter the raw material mixture. The sintered body 'i 2a~75~9 _ - 13 -was sufficiently pulverized with a porcelain mortar so as to prepare a powdery material. When the powdery material was identified by means of an X-ray diffractometry, various minerals were found in the resultant powdery material, as denoted by symbols CA5 to CAs~ in Table 1. Incidentally, the abbreviations shown in Table 1 and in the following description denote:
C3NzA5 ... 3CaO.2Na20.5Al203 NS ... Na2SO4 NA ,,, Na2O Al203 C4A3S ... 4CaO.3Al203.SO3 Table 1 raw material composition mineral formation (wt%) (wt%) Symbol Feature C3N2A5NS NA C4A3S Na2OA~2O3 CaO so3 CAs NA 4.250.75 95 0 36.961.8 0.9 0.4 95%
CA20 NA 34 6 60 0 30.558.9 7.2 3.4 60%
CA40 NA 68 12 20 23.355.7 14.2 6.8 20%
CA50 NA 85 15 0 0 19.754.0 17.8 8.5 0%
CA51C4A3S 84.1514.85 0 1 19.554.0 18.0 8.5 1%
CA60C4A3S 68 12 0 20 15.753.2 21.6 9.5 20%
CA80C4A3S 34 6 0 60 7.951.7 29.1 11.3 60%
CAg9C4A3S 0.85 0.15 0 99 0.250.2 36.5 13.1 99%
C~
- 202756q As seen from Table 1, the sintered bodies of samples CAs to CA50 were found to contain 4.25 to 85% of C3N2A5. 0.75 to 15% of NS and 0 to 95% of NA.
The sintered body contained in the cement setting accelerator of the present invention permits controlling the setting time of a cement paste while maintaining a predetermined mechanical strength of the cement composition. As described previously, the setting is promoted by the increase in the NA content of the sintered body. On the other hand, the setting rate of C3NzA5 is lower than that of NA. This is because C3NzA5 enables the cement composition after the setting to exhibit a greater mechanical strength. Incidentally, NS is a reaction product between Na20 and S03 serving to improve the reactivity of CaO in the process of forming 3CaO.2Na20.5Al203 and Na2O.Al2O3, as described previously.
In other words, NS is not particularly relevant to the setting and hardening of the composition.
The second embodiment at cement setting accelerator according to the invention is very close to the first embodiment thereof, the sole difference being that the raw material mixture, which is sintered in the first embodiment is not sintered in the second. To be more specific, the composition of the second embodiment is the same as that of the first, except that 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime powder are added in the accelerator of the second embodiment to 100 parts by weight of a powdar mixture consisting of 4.25 to 85% of 3CaO.2NazO.5Al2O3, 0.75 to 15%
of Na2SO~, and at most 95% of Na20.Al203. In both embodiments, the reasons for the mixing ratio of the components of the cement setting accelerator are the same.
The cement setting accelerator of the second embodiment is somewhat inferior to the first, in the effect of promoting the setting and hardening of a cement composition, but is superior to the conventional cement setting accelerator in ~ 0~ 7~b9 the particular effect noted above.
In the present invention according to the aforementioned third embodiment, a sintered body is used as a main component of the cement setting accelerator, as in the first embodiment. However, the sintered body used in the third embodiment and containing 3CaO.2Na20.5A1203, Na2SO4 and 4CaO.3Al203.SO3 differs in composition from that used in the first. To be more specific, the sintered body used in the third embodiment contains 0.85 to 84.15% of 3CaO.2Na20.5Al203, 0.15 to 14.85% of Na2SO4 and 1 to 99% of 4CaO.3Al203.SO3. Preferably, the sintered body should contain to 8.5 to 84.15% of 3CaO.2Na20.5Al203, 1.5 to 14.85%
of Na2SO4 and 1 to 90% of 4CaO.3Alz03.SO3. The reaction to form 4CaO.3Al203.SO3 within the sintered body is as follows:
A
8A~2O3 + 3Na2O + 7CaO + 2SO3 3CaO-2Na2O-5A~2O3 + Na2SO4 + 4CaO-3A~2O3-SO3 The reaction given above takes place in the case where the raw material contains at most 19.5% of Na2O
and at least 18.0% of CaO. The formation of 4CaO-3A~2O3-SO3 is increased with decrease in the Na2O
content and with increase in the CaO content of the raw material. In the case of using the sintered body according to the third embodiment, the setting o~ the cement paste is retarded with increase in the content of 4CaO-3A~2O3-SO3, but is promoted with increase in the content of 3CaO-2Na2O 5A~2O3. The mineral components of the sin-tered body are substantially the same in the effect given to the mech~n;cal strength of the cement com-position after the setting. In an extreme case where Na2O is not contained in the raw material, 4CaO-3A~2O3-SO3 is formed in an amount of 100%. In this case, the setting of the cement paste is so much retarded as to make it substantially impossible to put the cement setting accelerator to a practical use.
Where the sintered body contains 99% of 4CaO-3A~2O3-SO3, however, the cement setting accelerator produces a practically satisfactory effect. Therefore the upper limit of the 4CaO-3A~2O3-SO3 is determined to be 99%, the lower limit of the 3CaO-2Na2O-5A~2O3 and Na2SO4 contents are determined to be 0.85% and 0.15%, respec-tively, because the ratio of 3CaO-2Na2O-5A~2O3 to Na2SO4 ~02756q should be 85 : 15 as described previously in conjunction with the first embodiment of cement setting accelerator.
On the other hand, the lower limit of the 4CaO.3Al2O3. S03 content is set at 1% in the present invention defined in the third embodiment so as to make the invention of this embodiment clearly distinct from the invention defined in the first embodiment. In this connection, the upper limits of the 3CaO.2Na2O.5Al2O3 and Na2SO4 contents are determined to ~e 84.15% and 14.85%, respectively.
The sintered body in the third embodiment at cement setting accelerator is pulverized into a powdery material, as in the first embodiment. The powdery sintered body should desirably have a specific surface area of 1500 to 8000 cm2/g. It should be noted that 5 to 70 parts by weight, preferably, 30 to 70 parts by weight, of an alkali metal carbonate powder, and at most 170 parts by weight, preferably, 10 to 150 parts by weight, of a lime powder are added to 100 parts by weight of the sintered body, and the mixture is mixed so as to obtain a cement setting accelerator according to the third embodiment. The reasons for the amounts of the alkali metal carbonate powder and the lime powder specified in this embodiment are a~in to those explained previously in conjunction with the first embodiment of the invention.
The overall invention in one of its aspects is directed to a method of manufacturing the aforementioned third embodiment of cement setting accelerator.
For manufacturing the cement setting accelerator, it is necessary to prepare first a sintered body contained as a main component in the cement setting accelerator. For preparing the sintered body, a raw material prepared by mixing a predetermined ratio of Na2O, Al2O3, CaO and S03 iS
heated at a predetermined temperature. The reactant materials of Na2O, Al2O3, CaO and S03 are those explained previously in conjunction with the method of manufacturing ~21569 the first embodiment of accelerator. To reiterate, sodium carbonate and sodium bicarbonate can be used as sources of Na2O. Al2(OH)3 can also be used as the Al2O3 material in addition to alumina. CaSO4, Al2tSO4)3, etc. can be used as the S03 material. Further, limestone, quick lime, etc. can be used as the CaO material. In order to obtain a sintered body of the composition defined in the present invention, it is necessary to use a raw mateial containing 0.Z to 19.5% of Na2O, 50.2 to 54.0% of A12O3, 18.0 to 36.5% of CaO
and 8.5 to 13.1% of SO3. Preferably, the raw material should contain 2.0 to 19.5% of Na2O, 50.6 to 54.0% of Al2O3, 18.0 to 34.8% of CaO and 8.5 to 12.6% S03. The raw material of the composition noted above should be sintered at 1150C
or more, preferably, at 1200C or more, as in the manufacture of the first embodiment of product. The sintering conditions are equal to those explained previously in conjunction with the manufacture of the first embodiment. The sintered body is pulverized into a powdery sintered body, and 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime powder are added to 100 parts by weight of the powdery sintered body so as to obtain a desired cement setting accelerator of the present invention.
The aforementioned fourth embodiment of cement setting accelerator within the present invention is very close to the third embodiment thereof, the sole difference being that a mixture of the individual raw materials, which are contained in the sintered body used in the third embodiment, is used in the fourth embodiment of the invention in place of the sintered body. To be more specific, 5 to 70% parts by weight of an al~ali metal carbonate powder and at most 170 parts by weight of a lime powder are added in the invention of claim 6 to 100 parts by weight of a powdery mixture consisting of 0.85 to 84.15%
of 3CaO.2Na2O.5Al2O3, 0.15 to 14.85% of Na2SO4 and 1 to 99%
of 4CaO.3Alz03. S03 SO as to prepare a desired cement setting accelerator. The reasons for the mixing ratio of the components as well as the preferred ranges of the contents of the individual components of the accelerator specified in relation to the fourth embodiment produce the same as in the case of the third embodiment. The cement setting accelerator of the fourth embodiment is somewhat inferior to that of the third, in the setting rate of the cement paste and the mechanical strength of the cement composition after the setting, ~ut is superior to conventional cement setting accelerators.
Fxperiment 2:
First grade reagents of sodium carbonate, alumina, ...
h'~' 2027~69 calcium carbonate and calcium sulfate, which are available on the market, were ùsed as the raw materials, as in Experiment 1. These raw materials were mixed as denoted by samples CA5l to CAgg in Table 1. As pointed out previously, CO2 is dissipated at 950C from sodium carbonate and calcium carbonate contained in the raw material mixture in the process of sintering the raw material mixture. In view of the dissipation, these sodium carbonate and calcium carbonate were used in excess amounts.
The raw material mixture was sintered and, then, the sintered body was sufficiently pulverized in a porcelain mortar. The pulverized sintered body thus prepared was identified by means of X-ray diffraction so as to confirm the mineral formation as denoted by symbols CA51 to CAgg in Table l.
The effect of the cement setting accelerator was confirmed as follows. Specifically, each of sintered bodies prepared as in Experiments l and 2 was pulverized until the pulverized particles had a diameter of 0.3 mm or less. Then, sodium carbonate and slaked lime were mixed with the pulverized sintered body in amounts shown in Table 2 so as to prepare a cement setting accelerator. On the other hand, a cement paste was separately prepared by sufficiently mixing in a synthetic resin container having an inner volume of 200 m~ a wate/cement mixture mixed at a ratio of 0.6.
The samples of the cement setting accelerator were added to 160 g of the cement paste in outer percentage by weight of 5, 8, 15 and 20%, respectively. The mixture was rapidly mixed with a spatula for about lO seconds so as to permit the cement setting accelerator to be mixed sufficiently with the cement paste. After the surface was smoothed, the mixed cement paste was allowed to stand still so as to measure the initial setting time and final setting time of the cement paste setting in accordance with the test method specified in JIS R5201.
In this test, a weight of 300 g was put on a setting tester. Table 2 shows the results. Table 2 also shows comparative experiment, i.e., use of a rapid setting agent CAo consisting of NA, sodium carbonate and slaked lime, and use of a cement setting accelerator CAo1 available on the market. Incidentally, the parenthe-sized symbols shown in Table 2, i.e., (CA20), (CA40), (ca6o)~ and (CA80), denote that the compositions equal to those of CA20, CA40, CA60 and CA80 were used simply as mixtures of the individual powdery components, not as minerals as in the symbols without the parentheses.
Table 2 Mineral Composition or Composition of Cement Symbol Mixture Composition (wt~) Setting ~ccelrator (wt%) _ mineral sodium slaked C3N2A5 NS NA C4A3S or carbonate line mixture CAo - - 100 - 40 20 40 CA5 4.250.75 95 - 40 20 40 CA50 85 15 - _ 60 20 20 CA51 84.1514.85 0 1 60 20 20 w CAgg 0.850.15 - 99 95 5 0 CAol 34 6 60 - 40 20 40 (CA20) 34 6 60 - 40 20 40 (CA40) 68 12 20 - 50 20 30 ~
(CA60) 68 12 - 20 70 20 10 rs (CA80) 34 6 _ 60 85 15 _ C~
(Continued Addition Amount of Cement Setting Accelerator to Cement (outer % by weight) 5 % 8 % 15 % 20 %
Symbol initial final initial final initial final initial final time time time time time time time time (min., (min., (min., (min., (min., (min., (min., (min., sec.) sec.) sec.) sec.) sec.)sec.) sec.) sec.) or or or or CAo 2 '60 'more 2 ' 60 'more 10"60 'more 10" 60 'more CA5 2'30"3:0' 2' 30' 15"10' - -CA20 2'30" 27' 1' 20' 15" 5' 10" 3' CA40 5' 27' 4' 14' 1'30" 5' 1' 3' CA50 10' 35' 5' 17' 2'30" 10' 1'30" 4' CA51 12 36 ' 6 ' 18 ' 2 ' 40" 10 ' 1 ' 40" 4 ' CA60 23' 47' 10' 22' 5' 15' 2' 5' CA80 33' 50' 20' 35' 7' 20' 6' 20' CAgg - - 30 ' 55 ' 15 ' 45 ' 10 ' 30 ' or or or CAol 12'60'more 3'60'more 10" 60'more 10" 10' or (CA20 ) 10 '50 ' 2 '60'more 10" 10' 10" 7 ' or or (CA40 ) 15 '60'more 2 '60'more 10" 10' 10" 5 ' 2 or (CA60) 12'60'more 2' 30' 15" 11' 30" 8' or or (CA80) 13'60'more 2'60'more 3' 17' 3' 15' C.r~
CD
As seen from Table 2, any kind of the cement setting accelerator of the present invention exhibits an excellent rapid setting property. Figs. 1 to 4 show the results of the experiments, covering the different adding amounts of the cement setting accelerator, respectively. It is clearly seen from Figs. 1 to 4 that the cement setting accelerator of the present invention exhibits an excellent rapid setting and hardening pro-perty. It is important to note that the cement setting accelerator of the present invention makes it possible to control the setting time by controlling the mineral composition and the adding amount of the cement setting accelerator. It should also be noted that the parenthe-sized samples of (CA20), (CA40), (CA60) and (CA80) were somewhat inferior to the samples of CA20, CA40, CA60 and CAgo without the parentheses in the rapid setting pro-perty and the hardening time, but were superior to the comparative experiment of CAo and CAol, though the parenthesized samples are not shown in the drawings.
Example 1:
A raw material containing 46.4% of sodium carbonate, 47.9% of alumina, 3.4% of limestone, and 2.3%
of anhydrous gypsum was prepared by suitably mixing powdery materials of alumina (A~2O3, 99.7%), sodium carbonate (Na2O, 58.2%), limestone (CaO, 53.2%; MaO, 0.5%; Fe2O3, 0.2%; and A~2O3, 0.1%) and anhydrous gypsum (CaO, 41%; SO3, 58.7%). The raw material was sufficiently mixed and, then, sintered in a sintering furnace at 1300C i50C for 30 minutes so as to obtain a sintered body.
The resultant sintered body was found to contain 80% of NA, 17% of C3N2A5, and 3% of NS. In other words, the sintered body was found to contain 34.1% of Na2O, 60.6% of A~2O3, 3.6% of CaO and 1.7% of SO3. Then, the sintered body was pulverized into a powdery material having a Blain specific surface area of 3500 cm2/g. A
cement setting accelerator was prepared by adding 60 parts by weight of sodium carbonate and 130 parts by weight of quick lime to 100 parts by weight of the powdery sintered body thus prepared. The resultant cement setting accelerator was applied to the face in the presence of spring water in a tunneling site as follows.
In the first step, cloth was applied to provisionally stop spring water at the rate of 400 to 1000 1/min/5 m2 in a freshet portion at the face In a tunneling site, followed by placing in a cavity of the cloth a cement composition prepared by mixing 20 parts by weight of the cement setting accelerator pre-pared as above with 100 parts by weight of the ordinary Portland cement. The portion where the cement composi-tion was placed was supported with a flat plate for about 2 minutes so as to completely stop the spring water, followed by applying a concrete spraying by the ~_ 2027~69 ordinary method. An additional spring water and fall of the concrete layer were not recognized at all after the treatment.
Example 2:
A raw material containing 32.2% of sodium carbonate, 44.9% of alumina, 13.S% of limestone, and 9.4% of anhydrous gypsum was prepared by suitably mixing powdery materials of alumina, sodium carbonate, limestone and anhydrous gypsum, as in Example 1. The raw material was sufficiently mixed and, then, sintered as in Example 1 so as to obtain a sintered body.
The resultant sintered body was found to contain 20% of NA, 68% of C3N2A5, and 12% of NS. In other words, the sintered body was found to contain 23.3% of Na2O, 55.7% of A~2O3, 14.2% of CaO and 6.8% of SO3.
Then, the sintered body was pulverized as in Example 1 into a powdery material having a Blain specific surface area of 3500 cm2/g. A cement setting accelerator was prepared by adding 60 parts by weight of sodium carbonate and 90 parts by weight of quick lime to 100 parts by weight of the powdery sintered body thus prepared. The resultant cement setting accelerator was used in a tunnel-boring site as follows.
In the first step, concrete was prepared by mixing a mixture consisting of 360 kg of the ordinary portland cement, 1020 kg of a fine aggregate, 686 kg of a coarse aggregate having a maximum size of 15 mm, and ~- 2027569 205 kg of water. The concrete thus prepared was transported by a track mixer to the face of a tunneling site and sprayed through a hose including a Y-shaped branched portion to the face by a compressed air. The Y-shaped branched portion was positioned about 3 m inside the tip of the blowing nozzle mounted at the tip of the hose. The cement setting accelerator prepared as above was also sprayed by a compressed air through one of the branches of the hose such that the cement setting accelerator was added in an amount of 3 to 10% by weight (outer percentage) based on the amount of the cement contained in the concrete.
The concrete mixed with the cement setting accele-rator was sprayed through the nozzle onto the ceiling and wall of the arching tunnel. The average thickness of the concrete layer formed on the wall of the tunnel was about 20 cm. The amount of the cement setting accelerator was 3.5% on the average based on the amount of the cement contained in the concrete. The average thickness of the concrete layer formed on the ceiling of the tunnel was 20 to 50 cm. The amount of the cement setting accelerator was 6.5% on the average based on the amount of the cement contained in the concrete. In the case of the ceiling portion where 40 to 100 1/min/5 m2 of spring water was recognized, the concrete layer fell off in spite of the increase in the addition amount of the cement setting accelerator to 7% based on the amount ~_ 2027569 of the cement contained in the concrete. However, the fall was prevented when the amount of the cement setting accelerator was further increased to 9%.
On the other hand, concrete was similarly sprayed, by using a rapid setting agent available on the market consisting of calcium aluminate, sodium aluminate, sodium carbonate and lime. The amount of the rapid setting agent was 5.0% in the case of the wall of the - tunnel and 9.0% in the case of the ceiling of the tunnel on the average based on the amount of the cement con-tained in the concreta. Further, it was impossible to prevent the sprayed concrete layer from falling off in the presence of spring water, though the amount of the rapid setting agent was increased up to 15%.
Example 3:
A raw material containing 10.7% of sodium carbonate, 41.3% of alumina, 30.8% of limestone, and 17.2% of dihydrated gypsum was prepared by suitably mix-ing powdery materials of alumina (A~2O3, 98.1%),sodium carbonate tNa2O, 58.2%), limestone (CaO, 54.0%; MaO, 0.3%; and Fe2O3 0.1%) and dihydrated gypsum (CaO, 36.1%, SO3 51.9%). The raw material was sufficiently mixed and, then, sintered in a sintering furnace at 1250C
i50C for 30 minutes so as to obtain a sintered body.
The resultant sintered body was found to contain 60% of C4A3S, 34% of C3N2A5, and 6% of NS. In other words, the sintered body was found to contain 7.9% of ` ~--2027~69 Na2O, 51.7% of A~2O3, 29.1% of CaO and 11.3% of SO3.
Then, the sintered body was pulverized into a powdery material having a Blain specific surface area of 3200 cm2/g. A cement setting accelerator was prepared by adding 15 parts by weight of sodium carbonate to 100 parts by weight of the powdery sintered body thus prepared. A concrete layer was repaired as follows by using the resultant cement setting accelerator thus pre-pared.
10Specifically, vertical shaft mixer having an inner volume of 200 liters and an air compression pump were installed besides a repair portion of a concrete slab on which a train runs every hour. A flowable concrete was prepared by keanding a mixture consisting of 370 kg of 15cement, 1150 kg of a fine aggregate, 675 kg of a coarse aggregate, 150 kg of water and 1.75 kg of a fluidizing agent available on the market per cubic meter of the concrete mixture. The flowable concrete thus prepared was forwarded through the pump into a polyethylene bucket disposed at the repair portion 50 m away from the location of the concrete mixer. Fifty liters of the flowable concrete was received by the polyethylene bucket having an inner volume of 100 ~. Then, 1.1 kg of the cement setting accelerator prepared in advance was added to the concrete received in the bucket, and mixing was carried out for 2 to 3 minutes by a handy type mixer. The content of the cement setting accelerator was 6% based on the amount of the cement contained in the concrete. The mixed concrete was placed on the repair portion, followed by applying a surface-finishing treatment so as to complete the repair. Since initia-tion of the concrete setting was recognized 25 minutes after the mixing of the concrete with the cement setting accelerator added thereto, the repair work was completed without difficulty. The compression strength of a test piece of the same material was measured 1 hour after completion of the repair work. The compression strength was found to be 35 kgf/cm2, which is high enough to withstand the running of a train.
Example 4:
An agent B containing 95% or more of C3N2A5 was prepared by sufficiently mixing the raw materials con-sisting of 42.8% of alumina, 26.6% of sodium carbonate, and 40.9% of limestone as in Example 1, followed by sin-tering the raw material mixture at 1300C i50C in a sintering furnace. Likewise, an agent A containing 98%
or more of NA was prepared by sufficiently mixing the raw materials consisting of 49% of alumina and 51% of sodium carbonate, followed by sintering the raw material mixture at 1250C i50C in a sintering furnace. Then, a cement setting accelerator was prepared by uniformly mixing 24 parts by weight of agent A, 13.6 parts by weight of agent B, 2.4 parts by weight of sodium sulfate available on the market, 20 parts by weight of sodium ` ~_ 2027569 carbonate and 45 parts by weight of slaked lime.
Concrete spraying was carried out as in Example 2 by using the cement setting accelerator thus prepared.
The average amount of the cement setting accelerator used based on the amount of the cement contained in the concrete was 4.0% in the wall of the tunnel and 8.0%
in the ceiling of the tunnel. In the water spring portion, fall of the concrete layer was prevented when the amount of the cement setting accelerator was increased to 12%.
[Effect of the Invention]
As described above in detail, the present invention provides a cement setting accelerator which permits the setting of cement to be carried out in a short time and also permits controlling the initial setting time of the cement composition over a range of about 30 minutes starting with the time immediately after the addition of the cement setting accelerator. It follows that the cement setting accelerator of the present invention can be effectively used for the spraying of mortar or concrete which is required to be viscous at the time of spraying and to be set rapidly after the spraying.
Also, since the initiation time of the cement paste setting can be controlled over a wide range as noted above, it is of course possible to use the accelerator of the present invention as the broadly used cement setting accelerator requiring a determination in advance 20~75~9 of the setting reaction.
What should also be noted is that the cement setting accelerator of the present invention can be used both in a wet method in which the accelerator is added to a cement paste and in a dry method in which the accelerator is mixed previously with the cement. It follows that the cement setting accelerator of the pre-sent invention can be effectively used in a method which is popular nowadays, i.e., the method in which a cement paste mixed previously is forwarded to the place of application and the cement setting accelerator is added to the cement paste forwarded to the place of application.
-
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A cement setting accelerator consisting of a composition comprising 100 parts by weight of a sintered powdery material containing 4.25 to 85% of 3CaO.2Na2O.5Al2O3, 0.75 to 15% by weight of Na2SO4, and 0 to 95% by weight of Na2O.Al2O3; 5 to 70 parts by weight of an alkali metal carbonate powder; and 0 to 170 parts by weight of a lime powder, relative to 100 parts by weight of said sintered powdery material.
2. A method of manufacturing a cement setting accelerator defined in claim 1, characterized by comprising the steps of sintering at 1150°C or more a raw material containing 19.7 to 36.9% of Na2O, 54.0 to 61.8% of Al2O3, 0.9 to 17.8% of CaO, and 0.4 to 8.5% of SO3 so as to obtain a sintered body; pulverizing the sintered body; and adding 5 to 70 parts by weight of an alkali metal carbonate powder and 0 to 170 parts by weight of a lime powder relative to 100 parts by weight of the powder sintered body obtained by the pulverization and subsequently mixing the resultant mixture.
3. A cement setting accelerator consisting of a composition comprising 100 parts by weight of a powdery mixture containing 4.25 to 85% of 3CaO.2Na2O.5Al2O3, 0.75 to 15% by weight of Na2SO4, and 0 to 95% of Na2O.Al2O3; 5 to 70 parts by weight of an alkali metal carbonate powder; and 0 to 170 parts by weight of a lime powder.
4. A cement setting accelerator consisting of a composition comprising 100 parts by weight of a sintered powdery material containing 0.85 to 84.15% of 3CaO.2Na2O.5Al2O3, 0.15 to 14.85% by weight of Na2SO4, and 1 to 99% of 5CaO.3Al2O3.SO3; 5 to 70 parts by weight of an alkali metal carbonate powder; and 0 to 170 parts by weight of a lime powder, relative to 100 parts by weight of the sintered powdery material.
5. A method of manufacturing a cement setting accelerator defined in claim 4, characterized by comprising the steps of sintering at 1150°C or more a raw material containing 0.2 to 19.5% of Na2O, 50.2 to 54.0% of Al2O3, 18.0 to 36.5% of CaO, and 8.5 to 13.1% of So3 so as to obtain a sintered body; pulverizing the sintered body; and adding 5 to 70 parts by weight of an alkali metal carbonate powder and 0 to 170 parts by weight of a lime powder to 100 parts by weight of the powdery sintered body obtained by the pulverization and subsequently mixing the resultant mixture.
6. A cement setting accelerator consisting of a composition comprising 100 parts by weight of a powdery material containing 0.85% to 84.15% of 3CaO.2Na2O.5Al2O3, 0.15 to 14.85% by weight of Na2SO4, and 1 to 99% of 4CaO.3Al2O3.SO3; 5 to 70 parts by weight of an alkali metal carbonate powder; and 0 to 170 parts by weight of a lime powder relative to 100 parts by weight of the powdery material.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7604989 | 1989-03-28 | ||
| JP1-76049 | 1989-03-28 |
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| Publication Number | Publication Date |
|---|---|
| CA2027569A1 CA2027569A1 (en) | 1990-09-29 |
| CA2027569C true CA2027569C (en) | 1995-09-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002027569A Expired - Fee Related CA2027569C (en) | 1989-03-28 | 1990-03-28 | Cement setting accelerator and method of manufacturing the same |
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| Country | Link |
|---|---|
| US (1) | US5160376A (en) |
| EP (1) | EP0416134A4 (en) |
| KR (1) | KR920700170A (en) |
| CA (1) | CA2027569C (en) |
| WO (1) | WO1990011257A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5512325A (en) * | 1994-10-28 | 1996-04-30 | Indresco Inc. | Non-slumping, pumpable castable and method of applying the same |
| US6313055B1 (en) | 1998-08-20 | 2001-11-06 | Harbison-Walker Refractories Company | Refractory castables containing thermal black |
| US6313056B1 (en) | 1998-08-20 | 2001-11-06 | Harbison-Walker Refractories Company | Non-slumping sprayable refractory castables containing thermal black |
| AU3110600A (en) | 1998-12-08 | 2000-06-26 | William J. Mcnulty Jr. | Inorganic cementitious material |
| US6758896B2 (en) | 1999-04-16 | 2004-07-06 | Hassan Kunbargi | Rapid hardening, ultra-high early strength portland-type cement compositions, novel clinkers and methods for their manufacture which reduce harmful gaseous emissions |
| US6113684A (en) * | 1999-04-16 | 2000-09-05 | Kunbargi; Hassan | Rapid hardening, ultra-high early strength Portland-type cement compositions, novel clinkers and methods for their manufacture which reduce harmful gaseous emissions |
| US6406534B1 (en) | 1999-04-16 | 2002-06-18 | Hassan Kunbargi | Rapid hardening, ultra-high early strength portland-type cement compositions, novel clinkers and methods for their manufacture which reduce harmful gaseous emissions |
| MY151884A (en) * | 2006-11-09 | 2014-07-14 | Denki Kagaku Kogyo Kk | Quick-setting admixture and spraying method using it |
| WO2017162700A1 (en) * | 2016-03-22 | 2017-09-28 | Sika Technology Ag | Composition based on calcium oxide |
| JP2019048729A (en) * | 2017-09-08 | 2019-03-28 | デンカ株式会社 | Bonding material composition and stimulating agent thereof |
| CN111205010A (en) * | 2020-03-27 | 2020-05-29 | 河南天平工程质量检测有限公司 | Early strength agent for pavement concrete |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4650523A (en) * | 1984-06-08 | 1987-03-17 | Onoda Cement Co., Ltd. | Cement accelerating agent |
| JPS6126538A (en) * | 1984-07-12 | 1986-02-05 | 太平洋セメント株式会社 | Accelerator |
| CN85108582B (en) * | 1984-10-30 | 1988-08-17 | 蓝圈工业有限公司 | Settable cementitious compositions |
| JPS62191454A (en) * | 1986-02-19 | 1987-08-21 | 三興コロイド化学株式会社 | Accelerator for wet spray method |
| JPS63206341A (en) * | 1987-02-23 | 1988-08-25 | 太平洋セメント株式会社 | Cement accelerator |
| JP2746912B2 (en) * | 1988-05-23 | 1998-05-06 | 日本セメント株式会社 | Quick-setting agent for shotcrete |
| JPH0725577B2 (en) * | 1989-06-16 | 1995-03-22 | 電気化学工業株式会社 | A quick-setting agent for wet spraying of cement mortar or concrete. |
| JPH0251456A (en) * | 1989-06-16 | 1990-02-21 | Denki Kagaku Kogyo Kk | Curing accelerator for spraying of cement mortar or concrete |
-
1990
- 1990-03-28 EP EP19900905650 patent/EP0416134A4/en not_active Ceased
- 1990-03-28 KR KR1019900702522A patent/KR920700170A/en not_active Application Discontinuation
- 1990-03-28 US US07/598,639 patent/US5160376A/en not_active Expired - Fee Related
- 1990-03-28 CA CA002027569A patent/CA2027569C/en not_active Expired - Fee Related
- 1990-03-28 WO PCT/JP1990/000413 patent/WO1990011257A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| US5160376A (en) | 1992-11-03 |
| WO1990011257A1 (en) | 1990-10-04 |
| CA2027569A1 (en) | 1990-09-29 |
| KR920700170A (en) | 1992-02-19 |
| EP0416134A1 (en) | 1991-03-13 |
| EP0416134A4 (en) | 1991-08-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |